Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON):

Solution:
import sys
import Queue

sys.setrecursionlimit(1000000)

def s(m, v, q):
    if q.empty(): return -1
    k, i, j = q.get()
    if i == len(m) - 1 and j == len(m[i]) - 1: return k
    if i > 0 and m[i - 1][j] == '.' and (i - 1, j) not in v:
        q.put((k + 1, i - 1, j))
        v.add((i - 1, j))
    if i < len(m) - 1 and m[i + 1][j] == '.' and (i + 1, j) not in v:
        q.put((k + 1, i + 1, j))
        v.add((i + 1, j))
    if j > 0 and m[i][j - 1] == '.' and (i, j - 1) not in v:
        q.put((k + 1, i, j - 1))
        v.add((i, j - 1))
    if j < len(m[i]) - 1 and m[i][j + 1] == '.' and (i, j + 1) not in v:
        q.put((k + 1, i, j + 1))
        v.add((i, j + 1))
    return s(m, v, q)
     
h, w = map(int, raw_input().split())
m = [raw_input() for _ in range(h)]
q = Queue.PriorityQueue()
q.put((1, 0, 0))
v = set((0, 0))
c = s(m, v, q)
if c == -1: print -1
else: print h * w - c - sum([r.count('#') for r in m])